<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../node_modules/vue/dist/vue.js"></script>
</head>
<body>
    <div id="root">
        <h2>今天天气很{{info}}</h2>
        <button @click="changeWeather">切换天气</button>
    </div>
    <script type="text/javascript">
        let vm = new Vue({
            el:'#root',
            data:{
                isHot:true,
            },
            computed:{
                info(){ 
                   return this.isHot?'炎热':'凉爽';
                },
            },
            methods: {
                changeWeather(){
                    this.isHot = !this.isHot;
                },
            },
            watch:{
                isHot:{
                    immediate:true,
                    handler(newValue,oldValue){
                        newValue=!oldValue;
                        console.log("监视属性");
                    }
                }
            },
        });
    </script>
</body>
</html>
